The present invention is directed to bicycles and, more particularly, to an apparatus for connecting bicycle chain links together.
Bicycle chains engage the front sprockets at the bicycle pedal crank and the rear sprockets at the rear wheel hub for transmitting the pedaling force from the pedal crank to the rear wheel hub. As shown in Japanese Utility Model Application No. 6-49955, typical bicycle chains comprise first and second outer link plates, first and second inner link plates disposed between the first and second outer link plates so that a portion of the first outer link plate overlaps a portion of the first inner link plate and a portion of the second outer link plate overlaps a portion of the second inner link plate, a connecting pin that extends through the portion of the first outer link plate that overlaps the portion of the first inner link plate and through the portion of the second outer link plate that overlaps the portion of the second inner link plate to connect the first and second outer link plates to the first and second inner link plate, and a roller surrounding the connecting pin between the first and second inner link plates. The connecting pin has an intermediate part and first and second ends, wherein recesses are formed at the tips of the first and second ends. The first and second ends are crimped to form expanded parts that engage the outer surfaces of the first and second outer link plates. The recesses formed at the tips of the first and second ends make it easier to form the expanded parts when the first and second ends are crimped to the outer plates.
To adjust the chain length, a chain connecting pin extracting tool is used to extract the connecting pin and thereby separate the links. A typical chain connecting pin extracting tool comprises a pin extractor in the form of a push pin that is moved back and forth by a screw, and a positioning jig that engages and positions a chain link so that the connecting pin aligns with the pin extractor. The screw advances the pin extractor to push the connecting pin out of the chain while the chain is supported by the jig. At that time, the expanded part of the connecting pin at the end pushed by the pin extractor breaks off in the form of a ring, and the connecting pin is pushed out of the chain. After the chain length has been adjusted, a special replacement connecting pin is pushed into the chain to reconnect the end links.
When pushing the connecting pin out of a conventional chain, the outer link plates can become deformed as the expanded part breaks. This can be attributed to excessive force on the outer link plates when the expanded part is broken. If the outer link plates become deformed in this manner, the replacement connecting pin may not be held properly at the deformed outer plate when the chain links are reconnected, thus resulting in the danger of a weakly connected chain.